1. Field of the Invention
This invention relates to a controlling device for a transmission, and more particular it relates to improvement of the controlling device for a manual transmission in which a predetermined speed-changing gear is selected by driving an operating mechanism with an actuator based on operation of a shifting lever and so on.
2. Related Background Art
A speed-changing mechanism (referred to as a xe2x80x9ctransmissionxe2x80x9d hereinafter) changes the ratio between the number of engine rotations and the number of wheel rotations to suitably transmit an output of the engine to the wheels corresponding to a running condition of the vehicle. A manual transmission performing speed-change based on the driver""s manual operating is one example of such transmission. The manual transmission generally includes a gear portion selecting one of plural pairs of the speed-changing gears, an operating mechanism for operating the gear portion, and a controlling device for controlling the operating mechanism, although it includes minor differences depending on the type of transmission.
For example, the gear portion of five forward shifts and one backward shift type includes first to fifth speed-changing gears and a backward gear. The operating mechanism of the synchromesh-type includes first to third sleeves, and first to third paired synchronizer rings (referred to as xe2x80x9cringxe2x80x9d hereinafter).
The controlling device includes, as shown in FIGS. 8 to 10, first, second and third fork shafts 71, 72 and 73 respectively supported by a transmission casing 80, a selecting member 78 to be engaged with one of three fork shafts, a shift actuator 81 for driving the fork shafts 71 to 73, a selecting actuator 76 for driving the selecting member 78, and a shifting lever 75 handled by a driver (in another type, a shifting switch (for example. button) is switched). Each of the fork shafts 71, 72 and 73 has at a lower portion of a tip end a fork (only 72a is shown) engaging with the fork engaging portion of the sleeve, and has an upper portion of the tip end a head portion 71b, 72b or 73b engaged by a fever portion 78b of the selecting member 78. At the rear part of the first, second and third fork shafts 71, 72 and 73. first, second and third locking mechanisms 86, 87 and 88 to be explained later are provided.
The fork shafts 71 to 73 and the selecting member 78 have been conventionally driven directly by the shifting lever 75. However, a hydraulic driving device or an electric motor controlled by a ECU etc. has been recently interposed between the fork shafts 71 to 73, and the selecting member 78 and the shifting lever 75. In this case, the shifting lever 75 functions as a shift commanding member to command the driver""s intention for the speed-changing to the ECU. So, it can be comprised of switch member such as a button, instead of the shifting lever 75 shown in FIG. 8.
For example, an oil hydraulic actuator is used as the hydraulic driving device. As shown in FIGS. 9 and 10, a selecting rod 78 extending from a cylinder 77 of a selecting actuator 76 has a piston portion 78a at a rear end thereof, and is advanced/retraced by a pressured oil supplied to a cylinder 77 at both sides of the piston portion 78a. The selecting rod 78 has, at a tip end thereof, a lever portion 78b to be engaged with the head portion 71b, 72b or 73b. A shifting rod 83 extends in a crossing manner with a selecting rod 78 from a cylinder 82 of a shifting actuator 81 disposed to cross the selecting actuator 76. It has a piston portion 83a at a rear end, and has an engaging portion 83b engaging with the selecting rod 78 at the tip end.
With advancement/retraction of the selecting rod 77 by the selecting actuator 76 based on command of the ECU, the lever portion 78b of the selecting member 78 engages with one of the head portions 71b, 72b and 73b of the fork shafts 71, 72 or 73. Then, the selecting actuator 76 and one of the first to third fork shaft 71 to 73 engaged by the selecting member 78 are shifted integrally by the shifting actuator 81 based on the operating of the shifting lever 75. Thus, one of the first, second and third sleeves is shifted axially to select one of the speed-changing gears.
A first, second and third locking mechanism 86, 87 and 88 are provided for the first, second and third fork shafts 71, 72 and 73 respectively. These locking mechanisms 86 to 88 lock the fork shafts 71 to 73 and the sleeves at shifted positions thereof corresponding to shifting of the shift, locking them at the neutral position thereof corresponding to operation of the shifting lever 75. The locking mechanisms 86 to 88 are comprised of, as shown in FIGS. 9 and 10, three sets of semi-spherical hall holes 86a1, 86a2 and 86a3, 87a1, 87a2 and 87a3, and 88a1, 88a2 and 88a3 respectively formed at rear end of the fork shafts 71, 72 and 73; three halls 86b, 87b and 88b respectively pressed into the hall holes of each fork shaft: and three springs 86c, 87c and 88c respectively biasing the ball toward the corresponding ball holes.
The operating mechanism (the sleeves, the rings) are held at a leftward or a rightward position by moving the piston portion 83a near to the stroke ends of the shift actuator 81 via the fork shafts 71 to 73. For, example, when the sleeve etc. have been moved to the leftward position or the rightward position, the ball 87b is pressed into the ball hole 87a3 or 87a1 to hold the fork shaft 72 or the sleeve at the meshed position.
To the contrary, holding the sleeve etc. which have been shift-drawn out from the speed changing gear at the neutral position is not easy. For holding the sleeve etc. at the neutral position, they need to be positioned at a predetermined axial position or in extremely narrow allowable ranges located at both sides thereof. The sleeve etc. are held at the neutral position via the fork shafts 71 to 73 by holding the piston portion 83a at the axially neutral portion in the cylinder 82. However, the piston portion 83a can be hardly held at the neutral position even by regulating supply/discharge of the pressured oil. Thus, stopped position of the sleeve etc. may offset delicately in the axial direction of the cylinder 82.
For example, assume the piston portion 83a is offset in the cylinder 82 slightly leftward from the neutral position in the shift drawing-out of the second sleeve. In this case, the central ball groove 87a2 of the second locking mechanism 87 offsets slightly leftward from the position opposing the ball 87b. As a result, the ball 87b being drawn out from the ball hole 87a3 or 87a1 abuts a right edge of the ball hole 87a2 to apply a rightward biasing force F1 to the fork shaft 72. However, a sliding resistance F2 applied from the cylinder 82 to the piston portion 83a is larger than the biasing force F1. For this reason, the fork shaft 72 can not move rightward, stopping at a position offset slightly leftward from the neutral position. Thus, the locking mechanism 87 does not function to hold the fork shaft 72 and the sleeve at the neutral position. If vibration is applied to the transmission in this condition, the sleeve etc. are pressed to the speed-changing gears to be damaged and deteriorated.
When the central ball hole 87a2 of the second locking mechanism 87 is shifted slightly rightward from the position opposing to the ball 87b, the above mentioned members move in the direction reverse to the above direction. The above mentioned circumstances are similar for the first and third fork shafts 71 and 73.
Also, the engaging portion 83b of the shifting rod 83 engaging with the selecting rod 78, an engaging portion between head portions 72b etc. and the lever portion 78b of the selecting member 78, and distance between the head portions 72b etc. and the locking mechanisms 87 may have working and assembling errors. In this case, even if the piston portion 83a stops at the central position in the cylinder 82 in the shift drawing-out of the sleeve, the central ball hole 87a2 offsets leftward or rightward from position opposing to the wall 87b. As a result, problems similar to the above problem occur.
The above disadvantages of the conventional art may be overcome by controlling pressured oil supply to the cylinder 82 delicately and/or increasing working and assembling accuracies of the engaging portion 83b, the engaging portion between head portions 72b etc. and the lever portion 78b, and the distance between the head portions 72b and the locking mechanisms 87. However, delicate controlling of the pressured oil by the shifting actuator 81 and/or high accuracy working and assembling increase the manufacturing cost of the controlling device.
The present invention has been made in view of the above circumstances and intends to provide a controlling device for transmission in which the locking action of the locking mechanism is not hindered by a part of the controlling device (for example, a shifting actuator), when a fork shaft i.e. an operating mechanism is held at a neutral position. Here, movement of the operating mechanism in the transmission is controlled by the shifting fork of the controlling device, and the operating mechanism is locked at the neutral position, via the shifting fork, by the locking mechanism of the controlling device. The inventors of the present invention, as result of various studying, have hit on not applying the sliding resistance of an actuator moving in the same direction as the fork shaft to the fork shaft.
That is, the controlling device for transmission of the present invention includes plural fork shafts each having a fork engaged with an operating mechanism for speed-changing assembled into a gear portion of a transmission; a selecting member selectively engaging with one of the plural fork shafts; a selecting actuator for moving the selecting member to selected moved positions in a selecting direction so that the selecting member engages with the fork shaft setting a predetermined speed-changing shift; a shifting actuator for shift-moving the operating mechanism by applying an acting load to the fork shaft engaged by the selecting member; and locking mechanism for locking the plural fork shafts at a shifted position(s) and a neutral position corresponding to a shifting operation range of the operating mechanism.
In such controlling device for transmission, the selecting actuator is constructed to move the selecting member to a non-engaging position not engaged by any of the plural fork shafts.
In the controlling device for transmission of the present invention, after the sleeve is shift drawn-out from the speed-changing gear to the neutral position by the shifting actuator, the selecting member is moved by the selecting actuator to the non-engaging position where an engaging portion thereof does not engage with an engaged portion of any of the fork shafts. Thus, all of the fork shafts 71 to 73 can move axially without being applied sliding resistance. As a result, the fork shafts are locked by the locking mechanism at the neutral position thereof, which can avoid the operating mechanism from being held at the neutral position thereof pressed onto the gear portion.
According to the present invention, in the transmission in which the operating mechanism is operated by the shifting actuator based on operating of the shift commanding member such as the shifting lever, dimensional variation between the neutral position of the operating mechanism determined by the shifting actuator and the neutral position of the fork shafts determined by the locking mechanism provided for the fork shafts can be adjusted or removed. Such variation can be adjusted by releasing engagement between the fork shafts and the selecting member and holding the fork shafts and the operating mechanism at the respective neutral positions.
Next, various embodying modes of the present invention will be explained.
The gear portion of the transmission can be comprised of plural (three, for example) sets of paired speed-changing gears. The synchromesh-type operating mechanism can be comprised of plural sleeves respectively mounted on a main shaft axially movable but non-rotatable circumferentially, to set the main shaft and the speed-changing gear in an integrally rotatable state, and plural sets of paired rings to make the number of speed-changing gear rotations equal to the number of sleeve rotations.
The plural fork shafts of the controlling device can be disposed in one plane in parallel to each other, or along one circle in parallel to each other, to be moved axially. Each fork shaft has, at one end thereof, a fork engaging with the sleeve and an engaged portion engaged by the selecting member. The engaged portions are preferably aligned axially.
One selecting member has an engaging portion selectively engaging with one of the fork shafts. When the fork shafts are disposed in one plane in parallel, the selecting member can be disposed in the same plane orthogonal to them and movable axially. In this case, the selecting member selectively engages with one of the fork shafts by the engaging portion provided at a tip end thereof during the axial, movement, and can assume the non-engaging portion located at one side of the selected moved positions aligned in one direction. Also, when plural fork shafts are disposed along the circle, the selecting member can be inserted into a hollow portion thereof to be operated. In this case, the selecting member selectively engages with one of the fork shafts at the engaging portion provided on an outer peripheral surface thereof during the rotation.
Here, the non-engaging position of the selecting member does not include the position of the selecting member where the engaging portion has disengaged from the preceding engaged portion but has not engaged with the succeeding engaged portion yet in the axial movement. At the non-engaging position, a dummy engaged member is preferably provided.
The selecting actuator moves the selecting member to one of the selected moved positions for causing it to engage with one of the shafts, and the non-engaging position for causing it not to engage with any of them. It can be constructed by a hydraulic driving device such as an oil hydraulic cylinder or an electric motor, both of which are controlled by a ECU controlled based on operation of the shift commanding member. For example, the oil hydraulic cylinder can be comprised of an inner cylinder in which a rear end of the selecting member is contained, an outer cylinder coaxially disposed with the inner cylinder, and a piston member disposed between the inner and outer cylinders and axially movable. The selecting member is moved to the selected moved position by controlling pressure within the inner cylinder in a moved state of the piston member in one direction, and is moved to the non-engaging position by controlling pressure within the inner cylinder in a moved state of the piston member in the other direction.
The electric motor can have an output shaft of which the rotated angle can be indexed. With fixing the selecting member on the output shaft, the electric motor can move the selecting member to the selected moved positions and the non-engaged position by indexing the rotated angle of the output shaft.
The shift commanding member can be the shifting lever actually shifted by the driver, or the switch such as a button not shifted but pressed by the driver. When the shifting lever is used, various shifting patterns can be adopted.
The shifting actuator is preferably comprised of an oil hydraulic cylinder controlled by a ECU based on operation of the shift commanding member. The shifting actuator sufficiently moves at least the fork shaft, which means it can move only the fork shaft or can move the selecting member and the selecting actuator together with the fork shaft.
The locking mechanism locks the fork shafts at the shifted positions and the neutral position. The neutral position can be located at one end of the shifted position, or at intermediate portion thereof. The locking mechanism can lock, at least when the selecting member is located at the non-engaging position, the plural fork shafts at the neutral position thereof. Also, the locking mechanism can lock, when the engaging portion engages with any of the engaged portion, the fork shafts with which the selecting member does not engage at the neutral position thereof. One locking mechanism can be provided for plural fork shafts, or plural locking mechanism can be provided corresponding to plural fork shafts.